Combat ground vehicles such as tanks, personnel carriers, and Bradley combat vehicles are vulnerable to mines of other explosive devices buried in the ground, which creates an upward blast when detonated, imposing very high upwardly directed forces on the vehicle, which may seriously injure or kill the seated occupants.
When the vehicle drops back down and impacts the surface, lower forces are imposed on the occupants.
While the vehicle structures have been designed to withstand such blasts, there is a lack of energy absorbing seat installations that can adequately protect the solders in these vehicles from severe or fatal injuries to neck, spine, pelvis, legs and internal organs.
If the seat is directly attached to the floor via solid structures, this acceleration results in the sudden vertical acceleration of the seated occupants with the vehicle, potentially causing severe spinal compression-induced injuries. Also, due to the extreme vertical accelerations, the lower legs and feet are thrown upwards if the feet are directly contacting the vehicle floor at the time of the explosion, typically causing severe leg and/or foot injuries, often resulting in the need for amputation of one or both of the legs of the injured person.
To accelerate the occupant safely in the event of such an explosion, adequate energy absorbing structure may be provided that separates the seat pan from the floor so that the blast induced acceleration of the vehicle floor is not fully transferred into the seat pan and the occupant seated thereon.
If there is plenty of space between the seat pan and the vehicle floor (i.e., 15 inches or more) a crushable energy absorber with a very low constant crush load can be used to protect all of the various size occupants, especially against the upper body injuries (such as lumbar spine compression); and the feet may not even touch the floor with such seats well spaced above the floor so that foot and lower leg injuries may also be eliminated.
However, combat vehicles in the field have much less space, in the range of 6 to 9 inches below the seat pan. Therefore, protecting all of the soldiers of various sizes and weights from the effect of explosive blasts when occupying a seat in the vehicle seats is a challenge.
Further complicating the design of a blast worthy seat installation is the fact that soldiers now range considerably in size and weight and may or may not be wearing a heavily loaded back pack up to 65 lbs. The 5th percentile female weighs 110 lbs. and is of a height of 5 feet, while the 95th percentile male weighs 223 lbs. and is 6′2″ in height, and the 50th percentile male weighs 172 lbs. and is 5′9″ in height.
Blast level tolerances are lowest for the 5th percentile female and highest for the 95th percentile male.
It is an object of the invention to better protect the occupant from the effects of an explosive blast by minimizing the injuries from the effects of a blast induced spinal compression, tibia (lower leg bone) compression and foot acceleration when a mine or other buried explosive device explodes under a combat vehicle, as well as possible injuries caused by the shock of the vehicle impacting the ground after being elevated by such an explosion.